Method and equipment for heating gas and maintaining a desired temperature in a plurality of feed ducts

ABSTRACT

A method and equipment for controlling the temperature of heated gas forced through a plurality of ducts from a heating chamber, in which each duct has an associated variable flap which sets the cross section of the duct and a temperature sensing device which retains the flaps in position such that a desired predetermined temperature of the gas forced through the ducts will be maintained.

[451 Sept. 12,1972

United States Patent Vernazza Lehane et al. .............236/9 A Lehane et al. .........t...236/9 A .236/11 X Beeston.....................236/9 A M 379 5556 wwww WW W 5 7(20 MMMA 4692 7587 222 R m g Tmmm mm U D M U WMTD E UD Q F D O APGQTT D D ONE mR na MHDR [72] Inventor: Julius Vernazza, Aachen, Germany Primary Examiner-Edward J. Michael [73] Assignee: H. Krantz, Aachen, Germany Attorney-Arthur B. Colvin [22] Filed:

[57] ABSTRACT A method and equipment for controlling the temperature of heated gas forced through a plurality of ducts from a heating chamber, in which each duct has an as- Dec. 4, 1970 [ll] Appl. No.: 95,245

[52] US. Cl. A [51] Int. sociated variable flap which sets the cross Section f [58] Field of the duct and a temperature sensing device which retains the flaps in position such that a desired [56] References Cited UNITED STATES PATENTS predetermined temperature of the gas forced through the ducts will be maintained.

2,440,052 4/1948 Lingen.......................236l9 A 2 Claims, 1 Drawing Figure METHOD AND EQUIPMENT FOR HEATING GAS AND MAINTAINING A DESIRED TEMPERATURE IN A PLURALITY F FEED DUCTS The invention concerns a method and equipment for the central heating of a gaseous treatment medium and includes a heating chamber designed for carrying out the method, with a burner controlled by an adjusting motor.

The central heating of a gaseous medium is used not only in heating buildings, but is is also of importance in heat drying and heat treatment machines.

Machines for hot-fixing webs of plastic are known, for example, where air circulated by a fan is blown through thejweb and conducted during its returnto the fan through a heating chamber in which the air is heated centrally by an open burning oil orgas flame.

Since the amount of air circulated permit of time is very .great in these machines, the flow cross section which is manually limited in order to guide the air through the heatingchamber, forms a considerable throttle resistance inthe heating chamber, which can only be-overcome'by a high driving power of the circulating fan. This power consumption is further increased by the fact that the air is conducted over several baffle plates to achieve. a thorough mixing of theportion heated by the flame and passing laterally thereof.

A machine for treating webs has already been sug gested where only a fraction of the treatment medium or air to be circulated is sucked in by suction fans through heating chambers, to be heated by burner flames and then fed into a pressure chamber from which the heated portion is fed through branch ducts to the individual treatment medium conduits to be circulated by associated fans.

By heating only a portion of the entire circulated treatment medium, small flow cross sections may be provided in which a close contact of the treatment medium with the burner flames is insured, suffice to adequately "limit the throttling losses in the heating chambers.

Frequently it is necessary for heat treatment gases-of different temperatures'to be provided at different times spread over the duration of a treatment. It may also be necessary to provide heat treatment gas of different temperature simultaneously, from different ducts. In

the invention is represented schematically in the drawing in a longitudinal section and will be described more fully below.

. Referring now to the drawing, the heating chamber 1 mounts on its end face 2 a gasburner 3which receives combustion air through line 4, heating gas through line Sand treating gas through ports .5. Burner 3 is connectedrto an adjusting motor 6 controlled by a regulator7.. g

A plurality of ducts 8 extend from heating chamber 1 and a secondary air duct 9 leadsinto each ofthe ducts 8. Aresistance theremometer 11 is positioned in each duct 8 in the path of the flow caused by a fan 10. Throttle flaps 12 controlled by adjusting motors 14 which also control potentiometer-s 13 determine the cross section of the ducts 8 and hence the flow therethrough.

Temperature regulators 15 are connected by leads 16 to the resistancethermometers 11 and by leads l7 to the adjusting motors 14. The potentiometers 13,

both cases it is necessary to influence the amount of energy to be released for heating.

The solution of this problem, which is not found in the prior art, is the object of the present invention.

For the central heating of a gaseous treatment medium, which is subdivided after heating into individual currents and, aftera secondary gas is added, is fed to consumers, the invention suggests for the solution of the problem, to proceed, before the secondary gas is added, to regulate the temperature so that the individual currents undergo individual throttling based on their temperatures after the addition of the secondary gas, the total amount of throttling influencing the amount of energy to be released for heating.

The method according to the invention has not only the advantage of maintaining the central heating of a treatment medium subdivided into individual currents, but it also permits individual temperature regulation of the individual currents, and hence influences the amount of energy to be released bythe burner.

which are connected in series, are connected by leads 18 with regulator 7 of adjusting motor 6.

The method of operation of the heating chamber, according to the inventiomis as follows.

If it is desired to increase the temperature of the heating medium fed through one or more of the ducts 8, the associated temperature regulator 15 is set to the required temperature. As a result, motor 14 adjusts flaps 12 and alsoadjusts potentiometer 13. The setting of potentiometer 13 will, through regulator 7 and motor 6, increase the gas flow to burner 3 to increase the temperature.

When the temperature in an associated duct has increased to the desired value, the thermometer will sense the temperature and send a signal to the regulator l5to again adjust the flaps so that the temperature in each duct can be maintained as desired.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. A heating chamber having a plurality of outlet ducts each providing a separate heated air path, a suction fan in each duct, a gas burner for said chamber, an adjusting motor controlling said burner to vary the' gas supplied thereto to vary the heat energy provided thereby, a throttle flap provided for each of said ducts to control the flow of heated gas through the associated duct, an adjusting motor controlling each of said throttle flaps, a potentiometer controlled by each of said flap adjusting motors, a temperature regulator associated with each of said flap adjiusting'motors, to set the associated flap to a desired position, a thermometer in each of said ducts to sense the temperature of the gas flowing therethrough, means to supply a secondary gas to each of said ducts between the throttle flap and the thermometer, means connecting each of said thermometers to an associated flap regulating regulator to vary the setting of the associated flap depending upon the temperature sensed, a regulator for said gas burner adjusting motor, and means electrically connecting said potentiometers in series with said bumer regulator to vary the heat energy provided thereby based on the setting of said potentiometers.

2. A method for the central heating of a gaseous treatment medium flowing into a heating chamber having an associated gas fed burner and having a plurality of individual outlet ducts each having a throttle flap to control the flow of heated gas therethrough, comprising the steps of adding a secondary gas to each of the individual ducts between the throttling flap and the outlet of the duct, sensing the temperature of the combined gaseous treatment medium and secondary gas and based on such temperature simultaneously varying the setting of the throttling flap and the gas flow to the chamber to determine the amount of heating energy provided in the heating chamber.

HI! i l 

1. A heating chamber having a plurality of outlet ducts each providing a separate heated air path, a suction fan in each duct, a gas burner for said chamber, an adjusting motor controlling said burner to vary the gas supplied thereto to vary the heat energy provided thereby, a throttle flap provided for each of said ducts to control the flow of heated gas through the associated duct, an adjusting motor controlling each of said throttle flaps, a potentiometer controlled by each of said flap adjusting motors, a temperature regulator associated with each of said flap adjusting motors, to set the associated flap to a desired position, a thermometer in each of said ducts to sense the temperature of the gas flowing therethrough, means to supply a secondary gas to each of said ducts between the throttle flap and the thermometer, means connecting each of said thermometers to an associated flap regulating regulator to vary the setting of the associated flap depending upon the temperature sensed, a regulator for said gas burner adjusting motor, and means electrically connecting said potentiometers in series with said burner regulator to vary the heat energy provided thereby based on the setting of said potentiometers.
 2. A method for the central heating of a gaseous treatment medium flowing into a heatiNg chamber having an associated gas fed burner and having a plurality of individual outlet ducts each having a throttle flap to control the flow of heated gas therethrough, comprising the steps of adding a secondary gas to each of the individual ducts between the throttling flap and the outlet of the duct, sensing the temperature of the combined gaseous treatment medium and secondary gas and based on such temperature simultaneously varying the setting of the throttling flap and the gas flow to the chamber to determine the amount of heating energy provided in the heating chamber. 